Next, we vary the number of available channels in JMM. Packet size is set to 512 bytes and the number of channels vary from 2 to 8. The result is shown in Figure 25. The net-work throughput increases significantly when the number of channels increases from 2 to 5, but the increase is less significant when the number of channels is from 6 to 8.
This shows that our channel selection scheme can properly choose channels to sepa-rate contending traffics to non-interfering channels. Therefore, a modesepa-rate number of channels (around 5) is sufficient to boost the performance of JMM.
CHAPTER 6
Conclusions
We have shown that the multi-path routing, when being harmonized with multi-channel capability, has great potential to achieve good performance for WMNs. We then design the JMM protocol which combines multi-channel link layer and multi-path routing to offer this benefit. Dividing the time into slots, JMM coordinates channel usage among slots using a receiver-based channel-assignment and schedules transmissions accord-ing to the routaccord-ing information. In the route discovery phase of our multi-path routaccord-ing protocol, we propose a GREQ forwarding strategy to reduce the broadcast messages.
In addition, we define a new routing metric which explicitly accounts for the disjoint-ness between paths and interference among links. According to this metric, it is easy to select two maximally disjoint paths with less interference. Our simulation results show that JMM yields a significant (more than 240%) end-to-end throughput improve-ment in WMNs as compared to single channel scenarios. In summary, JMM efficiently increases the performance by decomposing the contending traffic over different chan-nels, different time, and different paths.
In the future, we plan to investigate the interplay between JMM and TCP. Furthermore, we hope to explore JMM in more detail using an implementation over actual hardware.
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